If you were using raw data, that is mxData with type="raw", then these fit indices are not returned by default so that the model estimates faster. These fit indices require a best-fitting comparison model that we call the Saturated Model. By default, OpenMx does not fit this model for you because it often doubles the amount of run-time. The saturated model is a model with all the means and covariances freely estimated as parameters. Future versions of OpenMx will have a helper function for making this model. I've attached the R file that defines this function for you to use. Running the attached R file defines a function called mxSaturatedModel that takes a simple mxModel, builds, and optionally fits the corresponding saturated model.